1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, such as a semiconductor laser, and more particularly to a method of manufacturing a semiconductor device for cutting out accurately each semiconductor device after a plurality of semiconductor devices are fabricated in a semiconductor wafer.
2. Prior Art
In the manufacture of a semiconductor device, such as a semiconductor laser, generally, after a plurality of semiconductor devices are fabricated in the substrate formed of a semiconductor wafer, markers are scribed in the surface of the semiconductor wafer with a scriber. The semiconductor wafer is cleaved along the scribed markers into semiconductor devices.
Among the conventional semiconductors, there is a semiconductor laser having a window structure as disclosed in Japanese Patent Public Disclosure No.06-338657, for example. According to this window structure, window layers for widening the band gap are formed near the end faces of the oscillator of a semiconductor laser, thereby making it possible to suppress the absorption of self-emitting radiation by the laser end faces. Thus, according to the semiconductor laser having the window structure, optical damage or destruction at the end portions of the oscillator can be prevented and the critical emission output can be improved.
The window layers can be formed by forming a multilayer structure for use as a semiconductor laser, then forming U-grooves for the window layers at specified positions, and refilling the U-grooves with a window material. After the window layers are formed, the multilayer structure for a semiconductor laser is subjected to stress and cleaved along planes determined by the crystal structure to thereby divide the window layers in the longitudinal direction of the U-grooves.
Before cleaving, the multilayer structure is scribed with a scriber to form markers in the surface thereof. The scribing accuracy of the scriber is on the order of several tens of .mu.m, whereas the minimum width of the U-groove for the divided window layer is about 10 .mu.m.
Therefore, with the conventional markers scribed with the scriber, it is not easy to obtain workpieces of accurate dimensions, so that variations tend to occur in the thickness dimension of the window layers.
As the scattering loss of the laser light increases with the increasing thickness of the window layers, for which reason the thickness of the window layers of each device to be sliced out should desirably be within a predetermined accuracy of thickness.
Accordingly, the object of the present invention is to provide a method of manufacturing a semiconductor device in which the markers for cleaving the semiconductor devices can be formed with high accuracy.